I suspect that the decision to call the search off was likely influenced by a common understanding of the parties to investigation that the loss of the aircraft was due to "willful human inputs" as already indicated in the preliminary report. Accepting this scenario, it is highly unlikely that the FDR/CVR would reveal anything that is not already known, both can easily be stopped by pulling a CB, and likely were just like the transponder. I would assume that were there any scenarios that would indicate any technical malfunction (like AF447) , there would be a much greater incentive to find the wreck whatever it takes.